Air purifying negative pressure device

ABSTRACT

A housing configuration includes a filter chamber having a purifying filter, a rear chamber in the back, and a fan chamber having a fan. In this housing configuration, a measurement port for purifying filter performance evaluation is provided in a substantially middle portion of the rear chamber, and a connecting portion connected to the measurement port and a cover for maintenance work are provided on the front surface of the housing. Provided as a result is an air purifying negative pressure device that is compact in configuration, can be installed with ease, and is capable of improving both the accuracy of an air purifying filter performance evaluation test and the workability of routine maintenance.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an air purifying negative pressure device that maintains negative pressure in a room while purifying the air in the room.

2. Description of the Related Art

A filter unit that captures fine particles in contaminated air with a high-efficiency particulate air (HEPA) filter and performs purification and discharge in order to make the contaminated air clean is widely known and used. The filter unit is mainly used in, for example, medical institutions and research facilities for the purpose of capturing and normalizing bacteria and viruses. According to JP 2001-178785 A, indoor air is purified by passage through a HEPA filter and discharged to the outside by an exhaust fan.

FIG. 10 illustrates the structure of a related art example of an air purifying filter unit for creating negative pressure in a hospital room. FIG. 10 is a cross-sectional view illustrating the structure of an air purifying filter unit 80 in the example of the related art. By driving a fan motor 86 and rotating a fan 85, the air in the hospital room is taken in and introduced into the air purifying filter unit 80 from a suction portion 82 of an exhaust HEPA filter unit. The intake air passes through a HEPA filter 81, and the air purified by the HEPA filter 81 is discharged to the outside through an exhaust port 87 by the rotation of the fan 85.

In addition, as for the exhaust HEPA filter unit, it is desirable to dispose a component requiring maintenance such as motor replacement and cleaning work on the discharge side of the HEPA filter. In a case where a fan, a fan motor, or the like that requires maintenance such as replacement is disposed on the suction side of the HEPA filter, the air that is yet to be purified by the HEPA filter passes through the fan, the fan motor, or the like, and thus viruses or bacteria floating in the air adhere to the fan, the fan motor, or the like. During subsequent filter unit maintenance, a worker may be infected by the viruses or bacteria on the fan, the fan motor, or the like. Accordingly, it is preferable to dispose a fan, a fan motor, or the like that requires maintenance such as replacement on the discharge side of a purifying filter.

In addition, in the case of a performance evaluation test for confirming the performance of the HEPA filter 81 or confirming that there is no problem in attaching the HEPA filter 81, a measurement port 88 for the performance evaluation test is temporarily attached to, for example, a part of the filter unit 80 and measurement is performed with the measurement port 88 connected to a particle sensor for fine particle measurement. Illustrated in the related art example illustrated in FIG. 10 is an example in which the measurement port 88 for a performance evaluation test is temporarily attached to a back surface side with respect to the suction portion 82.

Accordingly, since the measurement port 88 is at a temporary attachment position, the purifying performance of the filter in the normal use state of the filter unit cannot be evaluated with high accuracy.

In addition, although measuring with the blowout surface of the HEPA filter 81 by using a removable cover on the back surface side with respect to the suction portion 82 on the front surface is conceivable, when the fan 85 is rotated in that case, contaminated air is suctioned into the filter unit from the opening of the removed cover on the back surface side, the contaminated air does not pass through the HEPA filter 81, and thus it is necessary to provide another fan on the upstream side of the HEPA filter 81.

From the above, it is desired to have a filter unit that enables a performance evaluation test in the normal use state of the filter unit and improves the workability of maintenance such as routine filter unit motor replacement, filter replacement, and cleaning.

SUMMARY OF THE INVENTION

The present invention provides an air purifying negative pressure device that is compact in configuration, can be installed with ease, and is capable of improving both the accuracy of an air purifying filter performance evaluation test and the workability of routine maintenance.

In order to solve the above problems, an air purifying negative pressure device as an example includes: a filter chamber including a suction portion provided on a front surface of a housing to suction fine particle-containing air in a room and a purifying filter purifying the air suctioned into the suction portion by passage to a back; a rear chamber including a duct providing an air flow path extending in a direction substantially orthogonal to a flow path direction of the air passed to the back through the purifying filter and a suction port provided at a substantially middle position of a front wall surface of the duct in a longitudinal direction to suction the air in the duct; a fan chamber including a fan suctioning the air flowing out of the rear chamber forward, a fan motor rotationally driving the fan, an exhaust port laterally discharging the air suctioned by the fan, and a cover allowing the front surface of the housing to be opened; and a connecting portion allowing a measuring instrument outside the housing to measure a purification performance of the purifying filter to be connected to the suction port from the front surface of the housing.

Provided according to the present invention is an air purifying negative pressure device that is compact in configuration, can be installed with ease, and is capable of improving both the accuracy of an air purifying filter performance evaluation test and the workability of routine maintenance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram illustrating a state of installation of an air purifying negative pressure device 100 in a first embodiment;

FIG. 2 is a cross-sectional view in which the internal structure of the air purifying negative pressure device 100 in the first embodiment is viewed from above;

FIG. 3 is a perspective view in which a bell mouth 14 in the first embodiment is viewed from a purified air flow D side;

FIG. 4 is a schematic diagram illustrating the measurement principle of a particle counter 60 in the first embodiment;

FIG. 5 is a graph illustrating a measurement result of the particle counter 60 in the first embodiment;

FIG. 6 is a configuration diagram illustrating a state of installation of an air purifying negative pressure device 200 in a second embodiment;

FIG. 7 is a configuration diagram illustrating a state of installation of an air purifying negative pressure device 300 in a third embodiment;

FIG. 8 is a configuration diagram illustrating a state of installation of an air purifying negative pressure device 400 in a fourth embodiment;

FIG. 9 is a configuration diagram illustrating a state of installation of an air purifying negative pressure device 500 in a fifth embodiment; and

FIG. 10 is a cross-sectional view illustrating the structure of an air purifying filter unit 80 in the example of the related art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Modes of implementation will be described in detail with reference to the drawings. However, the present invention is not limited to the description of the following modes of implementation. It is easily understood by those skilled in the art that specific configurations thereof can be changed without departing from the idea or purpose of the present invention.

The position, size, shape, range, number, and so on of each element illustrated in the drawings and so on represent an example for facilitating the understanding of the invention, and the position, size, shape, range, and number of each element are not limited to those disclosed in the present specification and drawings. Those can be modified as appropriate in accordance with each mode of implementation. It should be noted that in the following embodiments, a plurality of similar elements are disposed and some of the elements will be described as representatives.

First Embodiment

FIG. 1 is a configuration diagram illustrating a state of installation of an air purifying negative pressure device 100 in a first embodiment. In FIG. 1 , the air purifying negative pressure device 100 is installed on a wall surface of a negative pressure room 1. The negative pressure room 1 is mainly assumed to be a hospital room or a bacterial laboratory and is a space for performing indoor air purification and discharge by driving a fan, which will be described later, and maintaining the indoor negative pressure to prevent infection from spreading.

The air purifying negative pressure device 100 takes in a contaminated air flow A containing dust to which viruses, bacteria, or the like are attached, purifies the air flow, and then discharges the air flow to the outside as a purified air flow B. Accordingly, the air purifying negative pressure device 100 is a device that purifies the air in the negative pressure room 1 by collecting dust in the air and prevents infection by maintaining the negative pressure.

The internal structure and operation of the air purifying negative pressure device 100 will be described in detail below. FIG. 2 is a cross-sectional view in which the internal structure of the air purifying negative pressure device 100 in the first embodiment is viewed from above. The air purifying negative pressure device 100 has a housing separated into the three chambers of a fan chamber 10, a filter chamber 20, and a rear chamber 30. In the disposition illustrated in FIG. 2 , the upper part in the drawing is the back surface and the lower part in the drawing is the front surface.

The filter chamber 20 has a front surface where a suction portion 22 is provided. A purifying filter 21 is provided in the filter chamber 20. The purifying filter 21 has a configuration in which glass fiber is used as a filter material and this configuration includes an outer frame holding the filter material by using a light metal such as alumite+clear-coated aluminum for the outer frame of the filter material. The configuration illustrates a general configuration of the purifying filter 21, and the present invention is not limited thereto. For example, an easily available material such as a non-woven fabric may be used as the filter material. The filter chamber 20 suctions indoor air from the suction portion 22 of the front surface, and the air flows out to the back through the internal purifying filter 21. In addition, the suction portion 22 can be opened and closed to the front.

The rear chamber 30 is provided on the back surface side of the filter chamber 20 and includes a duct that provides an air flow path extending in a direction substantially orthogonal to the flow path direction of the air passed to the back through the purifying filter 21. In FIG. 2 , air is sent out to the right side of FIG. 2 on the back surface side of the filter chamber 20.

The fan chamber 10 is provided beside the filter chamber 20 and in front of the rear chamber 30. The fan chamber 10 is an exhaust chamber. As for this exhaust chamber, a bell mouth 14 is provided at a suction port from the rear chamber 30 and a fan 12 is provided inside. The fan chamber 10 is provided with a fan motor 11 rotationally driving the fan 12, a motor fixing seat 15 where the fan motor 11 is fixed, a duct flange 13 as an exhaust port, and a cover 42 on the front surface.

The fan 12 is a rotary blade provided with a rotary shaft rotationally driven by the fan motor 11 and a plurality of fins having a predetermined shape around the rotary shaft (for example, four fins in the case of four blades). Negative pressure conditions can be optimized by designing the rotation speed of the fan motor 11 and the fin diameter provided in the fan 12 together with the bell mouth 14, which will be described later.

In FIG. 2 , the contaminated air flow A is taken into the suction portion 22 of the air purifying negative pressure device 100. Then, the contaminated air flow A is purified by the purifying filter 21 in the filter chamber 20 and flows out to the rear chamber 30 in the back as a purified air flow C. The purified air flow C flows in the rear chamber 30 extending substantially orthogonal to the flow path direction of the air passed through the purifying filter 21, is drawn in by the suction of the fan 12 as indicated by a purified air flow D, and is taken into the fan chamber 10 in front of the rear chamber 30.

By the fan 12 rotating, the purified air flow D in the fan chamber 10 is discharged to the outside as the purified air flow B through the bell mouth 14 and the duct flange 13. The fan 12 is rotationally driven by the fan motor 11, purifies the indoor air by suctioning the air from the inside of the room through the air flow path of the filter chamber 20, the rear chamber 30, and the fan chamber 10, and discharges the air from the duct flange 13 as an exhaust port to keep the room under negative pressure.

The bell mouth 14 is a suction unit for adjusting the pressure of suction into the fan chamber 10. FIG. 3 is a perspective view in which the bell mouth 14 in the first embodiment is viewed from the purified air flow D side. The inner diameter of the bell mouth 14, the outer diameter of the fin of the fan 12, and the rotation speed of the fan 12 are designed appropriately. As a result, as a negative pressure-efficient air flow, the suction pressure of the fan chamber 10 can be made more efficient with respect to the drive power of the fan motor and indoor negative pressure degree adjustment is also possible.

Each of the filter chamber 20, the rear chamber 30, and the fan chamber 10 forms a partitioned box shape. As a result, the contaminated air flow that is yet to be purified by the purifying filter 21 is partitioned so as not to flow out to the pre-exhaust fan chamber 10 and, as an air purifying device, the function of air purification is satisfied reliably. Further, manufacturing and assembly processes are simplified by the combination of the three chambers.

The air purified by the purifying filter 21 is taken into the rear chamber 30. In the rear chamber 30, a measurement port 40 is provided on the air flow path where the purified air flow C flows to the purified air flow D by the rotational suction of the fan 12. The measurement port 40 is a suction port provided on the air flow path of flow from the purified air C to D and at a substantially middle position of the front wall surface of the duct in the longitudinal direction. In a case where the position of the measurement port 40 is too close to either the purifying filter 21 or the fan 12, dust near the purifying filter 21 or the fan 12 may be detected and a decline in detection accuracy may arise. Accordingly, the position of the measurement port 40 is preferably a substantially middle position between the purifying filter 21 and the fan 12 on the air flow path in the rear chamber 30.

A tube 41 can be connected to the measurement port 40. A front end portion 41 a of the tube 41 is disposed on the front surface of the air purifying negative pressure device 100 and is a connecting portion where a particle counter 60 can be connected to the outside of the device.

The particle counter 60 is a measuring instrument capable of measuring a fine particle size, the number of particles, and so on and acquires the performance evaluation measurement value of the purifying filter 21. FIG. 4 is a schematic diagram illustrating the measurement principle of the particle counter 60 in the first embodiment. The air flow in the rear chamber 30 is drawn into the particle counter 60 with a predetermined suction force via the tube 41. The air flow drawn in from the inside of the rear chamber 30 is discharged into the particle counter 60 by a nozzle 61, and the discharged air flow is irradiated with laser light from a laser light source 62. In a case where fine particles are contained in the air flow irradiated with the laser light, the laser light is scattered by the fine particles. Fine particle detection can be performed by forming an image of the degree of scattering of the laser light with a condenser lens 63 and detecting it with a light receiving element 64.

The measurement result illustrated in FIG. 5 can be obtained from the measurement principle illustrated in FIG. 4 . FIG. 5 is a graph illustrating a measurement result of the particle counter in the first embodiment. A pulse waveform as illustrated in FIG. 5 is obtained from the output voltage of the detection result of the light receiving element 64, the magnitude of the peak indicates a fine particle size, and the pulse count indicates a fine particle count. As illustrated in FIG. 5 , the performance of the purifying filter 21 can be measured by measuring the particle size and number of fine particles in the air. However, the particle counter 60 does not depend on the detection principle and measurement result configuration illustrated in FIGS. 4 and 5 .

As described above, the air purifying negative pressure device 100 in the first embodiment is capable of measuring the air flow in the rear chamber 30 on the air flow path in a normal use state. As a result, a performance evaluation test in the normal use state of the purifying filter 21 can be accurately executed from the front surface side of the device housing.

In addition, in FIG. 2 , by opening the cover 42 disposed on the front surface, maintenance work such as replacement of the fan 12 and the fan motor 11 and cleaning of the inside of the air purifying negative pressure device 100 can be performed from the front surface side of the air purifying negative pressure device 100. As described above, both the performance evaluation test in the normal use state of the purifying filter 21 and the maintenance work can be performed from the front surface side of the device housing, and the workability is improved.

By being configured as described above, the air purifying negative pressure device of the present embodiment has the effect of reducing the amount of viruses or bacteria in the negative pressure room and weakening infectivity by collecting dust to which the viruses or bacteria in the negative pressure room are attached with the purifying filter 21. In addition, by discharging the air purified by the purifying filter 21 to the outside, the air purifying negative pressure device of the present embodiment has the effect of preventing infection by the viruses or bacteria in the negative pressure room from spreading to the outside.

In addition, as illustrated in FIG. 2 , the air purifying negative pressure device 100 has a housing where the filter chamber 20 and the fan chamber 10 are disposed in parallel and the rear chamber 30 is disposed in the back. The rear chamber 30 is a flow path member provided for forming an air flow path from the filter chamber 20 to the fan chamber 10 and fits at a depth of approximately 70 to 100 mm. Accordingly, the air purifying negative pressure device 100 can be practically used as a thin and compact device housing even with the filter chamber 20 and the fan chamber 10 disposed in front of the rear chamber 30. In addition, each of the three chambers of the filter chamber 20, the rear chamber 30, and the fan chamber 10 is manufactured, the three chambers are finally combined into the housing, and thus the manufacturing process is easy.

From the above, the air purifying negative pressure device 100 configured as a compact device housing can be easily installed on an indoor wall surface and is improved in workability as described above. Accordingly, a general hospital room or the like can be easily turned into an infectious disease control room and maintenance is also easy.

According to the first embodiment, the housing configuration includes the filter chamber 20 having the purifying filter 21, the rear chamber 30 in the back, and the fan chamber 10 having the fan 12. In this housing configuration, the measurement port 40 for purifying filter performance evaluation is provided in the substantially middle portion of the rear chamber, and the connecting portion 41 a connected to the measurement port 40 and the cover 42 for maintenance work are provided on the front surface of the housing. Provided as a result is the air purifying negative pressure device that is compact in configuration, can be installed with ease, and is capable of improving both the accuracy of an air purifying filter performance evaluation test and the workability of routine maintenance.

Further, by appropriately designing the correspondence relationship of the inner diameter of the bell mouth 14, the fin diameter of the fan, and the rotation speed of the fan as described above, the suction pressure of the fan chamber 10 can be made more efficient with respect to the drive power of the fan motor and indoor negative pressure degree adjustment is also possible. This leads to the effects of a reduction in fan motor drive power, a decrease in carbon emissions attributable to drive power, global warming prevention, and environmental preservation resulting in the realization of a sustainable society.

Second Embodiment

Hereinafter, an air purifying negative pressure device 200 in a second embodiment will be described. FIG. 6 is a configuration diagram illustrating a state of installation of the air purifying negative pressure device 200 in the second embodiment. In the second embodiment, components identical to those in the first embodiment will not be described. The second embodiment differs from the first embodiment in that a port guard 50 as a barrier is provided on the downstream side in the flow direction of the air that flows around the measurement port 40.

Although air flow measurement is performed with air suctioned from the measurement port 40 to the external particle counter 60 in FIG. 6 , in some cases, the air flow velocity is excessively high and the air flow cannot be suctioned well into the measurement port 40. By providing the port guard 50 in a case where the air flow velocity around the measurement port 40 is excessively high, the air flow velocity around the measurement port 40 can be reduced and the particle counter is capable of accurate measurement. The port guard 50 is a rectifying member having an L-shaped cross section.

According to the second embodiment, by providing the port guard 50 as a rectifying member, it is possible to prevent the occurrence of a measurement problem in suctioning air into the particle counter 60 provided outside and adjust performance evaluation measurement accuracy in measuring the performance of the purifying filter 21.

Third Embodiment

Hereinafter, an air purifying negative pressure device 300 in a third embodiment will be described. FIG. 7 is a configuration diagram illustrating a state of installation of the air purifying negative pressure device 300 in the third embodiment. In the third embodiment, components identical to those in the first embodiment will not be described. The third embodiment differs from the first embodiment in that a port guard 51 as a barrier is provided on the downstream side in the flow direction of the air that flows around the measurement port 40.

Although air flow measurement is performed with air suctioned from the measurement port 40 to the particle counter 60 in FIG. 7 , in some cases, the air flow velocity is excessively high and the air flow cannot be suctioned well into the measurement port 40. The port guard 51 is a rectifying member having an L-shaped cross section with an opening portion 51 a provided on the downstream side in the air flow direction. The position of the opening portion in the longitudinal direction (vertical direction on the paper surface) is determined in view of the position of the measurement port. By providing the opening portion 51 a on the downstream side as in the case of the port guard 51 illustrated in FIG. 7 , the air flow around the measurement port 40 can be suctioned well and a decline in measurement accuracy in which more fine particles are detected than in a normal air flow path due to dust accumulation in the port guard 50 illustrated in the second embodiment can be suppressed.

According to the third embodiment, by providing the port guard 51 as a rectifying member, it is possible to prevent the occurrence of a measurement problem in suctioning air into the particle counter 60 provided outside, adjust performance evaluation measurement accuracy in measuring the performance of the purifying filter 21, and prevent a decline in measurement accuracy attributable to dust accumulation in the port guard.

Fourth Embodiment

Hereinafter, an air purifying negative pressure device 400 in a fourth embodiment will be described. FIG. 8 is a configuration diagram illustrating a state of installation of the air purifying negative pressure device 400 in the fourth embodiment. In the fourth embodiment, components identical to those in the first embodiment will not be described. The fourth embodiment differs from the first embodiment in that a port guard 52 rectifying the air flow flowing around the measurement port 40 is provided.

Although air flow measurement is performed with air suctioned from the measurement port 40 to the particle counter 60 in FIG. 8 , in some cases, the air flow velocity is excessively high and the air flow cannot be suctioned well into the measurement port 40. As illustrated in FIG. 8 , the port guard 52 is a mountain crest-shaped rectifying member. By forming the mountain crest shape as illustrated in FIG. 8 , the air flow around the measurement port can be rectified and a decline in measurement accuracy in which more fine particles are detected than in a normal air flow path due to dust accumulation can be suppressed. Further, the air flow passing above the port guard 52 can be rectified and pressure loss in the rear chamber 30 can be suppressed.

According to the fourth embodiment, by providing the port guard 52 as a rectifying member, it is possible to prevent the occurrence of a measurement problem in suctioning air into the particle counter 60 provided outside, adjust performance evaluation measurement accuracy in measuring the performance of the purifying filter 21, and suppress pressure loss in the rear chamber 30.

Fifth Embodiment

Hereinafter, an air purifying negative pressure device 500 in a fifth embodiment will be described. FIG. 9 is a configuration diagram illustrating a state of installation of the air purifying negative pressure device 500 in the fifth embodiment. In the fifth embodiment, points identical to those in the first embodiment will not be described. The fifth embodiment differs from the first embodiment in that a port guard 53 rectifying the air flow flowing around the measurement port 40 is provided.

Although air flow measurement is performed with air suctioned from the measurement port 40 to the particle counter 60 in FIG. 9 , in some cases, the air flow velocity is excessively high and the air flow cannot be suctioned well into the measurement port 40. As illustrated in FIG. 9 , the port guard 53 is an upright rectifying member provided such that the air flow in the rear chamber 30 does not directly hit the measurement port 40. By forming the upright shape as in FIG. 9 , turbulence is generated in the rear chamber 30 and, if there is a leak in the air purifying negative pressure device 500, the fine particles can be diffused into the rear chamber 30 by the turbulence. The measurement accuracy of the particle counter 60 is improved by diffusing the fine particles in the rear chamber 30 and reducing the air flow velocity around the measurement port 40.

According to the fifth embodiment, by providing the port guard 53 as a rectifying member, it is possible to prevent the occurrence of a measurement problem in suctioning air into the particle counter 60 provided outside and, if there is a leak in the air purifying negative pressure device 500, the fine particles can be diffused into the rear chamber 30 by the turbulence. The measurement accuracy of the particle counter 60 is improved by diffusing the fine particles in the rear chamber 30 and reducing the air flow velocity around the measurement port 40.

In the above, modes of implementation in which the port guards 50 to 53 are provided around the measurement port 40 with various shapes have been described in the second to fifth embodiments. As described above, the air suction amount at the measurement port 40 can be adjusted and the performance measurement accuracy of the purifying filter 21 can be optimized by designing the shapes of the port guards 50 to 53, the inner diameter of the bell mouth 14, the fin diameter of the fan 12, and the rotation speed of the fan 12 in association with each other. By optimizing the performance measurement accuracy of the purifying filter 21, the air purifying negative pressure device more efficient in terms of drive power and design man-hours is provided.

In addition, the pressure of exhaust to the duct flange 13 can be adjusted and the degree of negative pressure by the air purifying negative pressure device can be optimized by adjusting the inner diameter of the bell mouth 14, the fin diameter of the fan 12, and the rotation speed of the fan 12 in association with each other.

It should be noted that the filter chamber and the fan chamber are laterally disposed in the housing configurations of the first to fifth embodiments and yet the chambers may be disposed above and below in an alternative housing configuration. In this case, the housing has a shape elongated in the up-down direction and the form is suitable for a case where an up-down disposition is preferable because of the constraints of an installation space elongated in the up-down direction. 

What is claimed is:
 1. An air purifying negative pressure device comprising: a filter chamber including suction portion provided on a front surface of a housing to suction fine particle-containing air in a room and a purifying filter purifying the air suctioned into the suction portion by passage to a back; a rear chamber including a duct providing an air flow path extending in a direction substantially orthogonal to a flow path direction of the air passed to the back through the purifying filter and a suction port provided at a substantially middle position of a front wall surface of the duct in a longitudinal direction to suction the air in the duct; a fan chamber including a fan suctioning the air flowing out of the rear chamber forward, a fan motor rotationally driving the fan, an exhaust port laterally discharging the air suctioned by the fan, and a cover allowing the front surface of the housing to be opened; and a connecting portion allowing a measuring instrument outside the housing to measure a purification performance of the purifying filter to be connected to the suction port from the front surface of the housing.
 2. The air purifying negative pressure device according to claim 1, further comprising a rectifying member performing air flow adjustment near the suction port, wherein the rectifying member is provided on the front wall surface of the duct.
 3. The air purifying negative pressure device according to claim 2, wherein the rectifying member has an L shape in which a surface orthogonal to the air flow path direction in the duct is provided on a downstream side of the suction port in the air flow path direction.
 4. The air purifying negative pressure device according to claim 3, wherein the rectifying member is provided with an opening portion in the surface orthogonal to the air flow path direction in the duct.
 5. The air purifying negative pressure device according to claim 2, wherein the rectifying member is disposed near the suction port by inclining a mountain crest-shaped member with respect to the air flow path direction in the duct.
 6. The air purifying negative pressure device according to claim 2, wherein the rectifying member has an upright shape in which a surface orthogonal to the air flow path direction in the duct is provided on an upstream side of the suction port in the air flow path direction.
 7. The air purifying negative pressure device according to claim 1, wherein the purifying filter is replaceable from the front surface of the housing by opening the suction portion.
 8. The air purifying negative pressure device according to claim 2, further comprising a suction unit at an inlet of suction from the rear chamber to the fan chamber, wherein performance evaluation accuracy of the purifying filter is adjustable by adjusting a shape of the rectifying member, an inner diameter of the suction unit, a fin diameter of the fan, and a rotation speed of the fan in association with each other.
 9. The air purifying negative pressure device according to claim 1, further comprising a suction unit at an inlet of suction from the rear chamber to the fan chamber, wherein a degree of negative pressure in the room is adjustable by adjusting an inner diameter of the suction unit, a fin diameter of the fan, and a rotation speed of the fan. 